Direct cylinder fuel injection system for internal combustion engines

ABSTRACT

A system for introducing fuel into the combustion chamber of an internal combustion engine which includes at least one piston reciprocating in a cylinder with a cylinder head closing the top of the cylinder forming a combustion chamber between piston and head. At least one intake valve and one exhaust valve are provided in the cylinder head. One or more fuel injectors communicate through the sidewall of each of the engine cylinders for injecting fuel during the piston intake stroke while the top of the piston is below the injection site. The fuel injector may be any suitable injector, typically of a low pressure type. The fuel injector is oriented to direct a spray of fuel droplets in the direction of the cylinder head and/or the closed exhaust valve to speed droplet evaporation and cool the exhaust valve. Engines using this system also have increased tolerance of low octane fuel and improved emission characteristics.

BACKGROUND OF THE INVENTION

This invention relates in general to improvements in internal combustionengines and, more specifically, to a system for directly injecting fuelinto an engine cylinder through the cylinder sidewall.

Over the years, a great deal of research and development effort has beenexpended toward achieving improved fuel efficiency together with reducedexhaust emissions in internal combustion engines. Higher compressionratios are usually beneficial in these areas. However, detonationrapidly becomes a problem unless high octane fuels or octane enhancingadditives are used. High octane fuels are costly, and the enhancingadditives often contribute to exhaust emission problems.

Many engine design and operational improvements have been made to allowhigher efficiency with lower octane fuels. These include improvements inignition control, in particular with computer controlled spark advancesystems, improvements in valve timing, improved fuel delivery systems,in particular fuel injection systems, and combustion chamber designenhancements.

Significant advancements have been made in combustion chamber design,such as are described in my copending U.S. patent application, Ser. No.07/995,785, filed Dec. 23, 1993.

Improvements in fuel delivery to these combustion chamber designs, orothers, would further improve engine efficiency. Fuel injection systemsin which fuel is indirectly injected as a spray either into a throttlebody and ducted to the combustion chambers or into intake ports feedingcombustion chambers are rapidly replacing carbureted systems. Undercomputer control, much more precise metering of fuel, improved fueldistribution and improved air delivery capacity, etc. are possible withfuel injection.

Single point injection systems where the fuel is injected into eitherthe induction manifold of the throttle body suffer many of the problemsgenerally associated with carburation. These include unequal mixturedistribution to different cylinders and deposition of fuel on manifoldwalls. Multi-point port fuel injection provides a more even fueldistribution but raw fuel is still a problem on port walls and intakevalves.

With direct fuel injection into the combustion chamber, the injector isordinarily installed in the cylinder head, often at the top center ofthe combustion chamber to provide optimum fuel spray with minimal wallwetting. To avoid waste of fuel, valve arrangements must be designed toprevent fuel loss through the exhaust port during scavenging. Port orthrottle body ;injection can utilize up to 720° of crankshaft rotationin a four-stroke engine. However, this sprays raw fuel onto the back ofa closed intake valve resulting in liquid fuel on the port walls andvalve and allows raw fuel to pass out of the exhaust port at overlap.This can also result in bore wall wetting, fouled spark plugs, wornpiston rings, incomplete combustion, misfire, etc.

Direct injection into the combustion chamber directly from the cylinderhead during the intake stroke has advantages over throttle bodyinjection. However, these injectors tend to be high in cost due thenecessity of resisting high chamber pressures and temperatures and oftencauses bore wall wetting resulting in excess piston ring wear, crankcasecontamination and elevated hydrocarbon emissions.

A number of different arrangements for injecting fuel directly orindirectly into combustion chambers have been developed. Fuel may beinjected into the side of the combustion chamber tangentially to cause arich mixture to swirl past the spark plug. While effective in industrialpower units running mainly at constant speed, difficulties incontrolling swirl and stratification throughout the range and speeds ofautomobile engines and the like has limited the usefulness of thisdesign. Other designs used a bowl-in-piston combustion chamber and anaxial injector with either early or late injection, relative to the timethe piston approaches top dead center. Maintaining an optimizedstratified charge over a wide range of power loading has provendifficult.

Direct injection systems often have problems with depositions of fueldroplets on the cylinder walls followed by variable and incompleteevaporation, poor mixing of fuel and air that results in fuel/airseparation problems. These produce cylinder to cylinder mixtureuniformity problems.

There is a continuing need for improvements in the fuel injection systemand its relationship to the combustion chamber to provide betteratomization, lower exhaust emissions and an improved tolerance for loweroctane fuel.

SUMMARY OF THE INVENTION

The above-noted problems are overcome, and advantages achieved, by afuel injection system for internal combustion engines in which at leastone injector is mounted in the sidewall of the cylinder so that fuel canbe injected through an opening in the cylinder sidewall while the pistonis in the intake stroke from about 40° after top dead center toapproximately 80° before top dead center on the compression stroke, sothat about 240° of crankshaft rotation is available. After the injectionphase, the piston travels toward top dead center, covering the injector,and ignition occurs. For best results, the injector is orientated so asto direct the injected spray toward the closed exhaust valve. This bothcools the exhaust valve and supplies heat to vaporize the spray,improving atomization.

The injector is not subjected to high temperatures or high pressure,simplifying injector design and allowing the use of a relatively lowcost injector. Fouling of the injector is greatly reduced, since it iscovered during actual combustion.

This arrangement provides improved combustion, resulting in lowerexhaust emissions, higher fuel efficiency and an increased tolerance forlower octane fuels. There is no overlap flow or crossflow ofhydrocarbons.

BRIEF DESCRIPTION OF THE DRAWING

Details of the invention, and of preferred embodiments thereof, will befurther understood upon reference to the drawing, wherein:

FIG. 1 is a schematic transverse vertical section view through onecylinder of an engine using the fuel injection system of this inventionon the cylinder side opposite the exhaust valve;

FIG. 2 is a schematic transverse vertical section view of an alternateembodiment having the injector on the same side as the exhaust valve;

FIG. 3 is a section view taken on line 3--3 in FIG. 2; and

FIG. 4 is a schematic transverse vertical section view of a secondalternate embodiment having two injectors on opposite sides of thecylinder.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 are schematic illustrations of a conventional internalcombustion engine 10 in which the fuel injection system of thisinvention could be used. Any suitable engine, automotive, marine,aircraft, stationery, etc. may use the fuel injection improvement ofthis invention. FIG. 1 is a transverse section through one cylinder 12in engine block 13 of engine 10, including components in the upperportion of the engine.

A conventional piston 14 is installed in cylinder 12 for reciprocationtherealong. The top of cylinder 12 is closed by a cylinder head 16having, in the embodiment shown, exterior cooling fins 18. A combustionchamber 20 is bounded by piston 14, head 16, intake valve 22 and exhaustvalve 24. A conventional spark plug 32 is provided to ignite theair/fuel mixture in combustion chamber 20.

Fuel is introduced into cylinder 12 by a fuel injector 34 which issupplied with fuel by a conventional pumping and metering system underconventional computer control (not shown). Fuel injector 34 is mountedin an opening in engine block 13 in communication with cylinder 12. Theassembly is shown in FIG. 1 during the intake stroke with exhaust valve24 closed and intake valve 22 open. Preferably, fuel injector 34 isorientated so as to direct the spray 26 of fuel droplets toward the faceof closed exhaust valve 24. This serves to both cool exhaust valve 24and to aid in rapid vaporization of the fuel spray droplets approachingor contacting the surface of the exhaust valve or valves.

As the piston stroke continues, the piston moves up past fuel injector34, intake valve 22 closes and the mixture of air and fuel is compressedinto combustion chamber 20 and the power stroke begins. Typically thelayout of valves and sparkplug may be as shown in FIG. 3, discussedbelow.

Any suitable fuel injector may be used as fuel injector 34. Since thefuel injector is not subjected to high temperature or pressure, arelatively low cost fuel injector may be used. Further, since the pistoncovers the fuel injector during combustion, much less fouling of theinjector will occur. With better atomization of the fuel, more uniformair/fuel mixing and cooler exhaust valve/chamber temperatures, thesystem can use lower octane fuels without detonation and fewerobjectional exhaust emissions will be produced. Exhaust valve 24, theexhaust seat and the valve guide will have a longer life due to cooleroperation.

An alternate location for fuel injector 34 is shown in FIG. 2. Block 13,cylinder 12, intake valve 22 and exhaust valve 24, etc. are as shown inFIG. 1. In this embodiment, injector 34 is mounted in block 34 on thesame side of cylinder 12 as exhaust valve and is positioned to directfuel spray 26 toward exhaust valve 24.

As seen in FIG. 3, in the embodiment shown a single exhaust valve 24 andtwo intake valves 22 are used, with a centrally located spark plug 32.If desired, only a single intake valve of larger diameter could be used,and two or more exhaust valves could be used, with the injected fuelsprayed in the general direction of the exhaust valves. As seen in FIG.3, head 16 may include squish pads 28 between valves 22 and 24 tocooperate with the upper surface of piston 14, as detailed in mycopending applications identified above.

A third embodiment of the fuel injection system of this invention isshown in FIG. 4. Here, the arrangement of block 13, cylinder 12, exhaustvalve 24, intake valve 22 and combustion chamber 20, etc., is generallysimilar to that shown in FIG. 1. Here, two injectors 34 are provided onopposite sides of cylinder 12, each directing a fuel spray toward closedexhaust valve 24.

While the arrangements shown in the drawing are preferred, injectors 34may be positioned and oriented differently, where suitable. For example,in some cases it may be preferred to orient at least one injector at anangle to the centerline of cylinder 12 to cause a swirling action. Wheretwo exhaust valves 24 are provided, each of the injectors 34 could beoriented to direct fuel against one of the exhaust valves. Of theembodiments shown, that of FIG. 2 is preferred because the fuel spraydirectly contacts the hot exhaust valve, vaporizes and is then entrainedin the intake airflow.

While certain preferred materials, dimensions and arrangements have beendetailed in conjunction with the above description of preferredembodiments, those can be varied, where suitable, with similar results.Other applications, variations and ramifications of this invention willoccur to those skilled in the art upon reading this disclosure. Thoseare intended to be included within the scope of this invention asdefined in the appended claims.

I claim:
 1. An improved system for injecting fuel into a cylinder of aninternal combustion engine which comprises;at least one cylinder with apiston therein for reciprocation in the cylinder; a cylinder headopposite the top of the piston; a combustion chamber between said pistonand said head; at least one exhaust valve and at least one intake valvein said cylinder head; at least one fuel injector mounted adjacent tothe side wall of said cylinder and located to inject substantially allinjected fuel into said cylinder toward said exhaust valve; and meansfor causing fuel to be injected during the intake period of said enginewhile the top of said piston is below said fuel injector.
 2. The systemaccording to claim 1 including a single exhaust valve, a single intakevalve and a single fuel injector.
 3. The system according to claim 2wherein said injector is on the side of said cylinder opposite saidexhaust valve.
 4. The system according to claim 2 wherein said injectoris on the same side of said cylinder as said exhaust valve.
 5. Thesystem according to claim 1 wherein at least two injectors are providedin said cylinder with said injectors oriented to inject fuel toward atleast one exhaust valve.
 6. In an internal combustion engine comprisingan engine block, at least one cylinder in said block, a piston in saidcylinder for reciprocation therealong, a cylinder head opposite an endsurface of said piston forming a combustion chamber between said headand said piston, at least one exhaust valve and at least one intakevalve in said head operatively connected to said combustion chamber,means for introducing fuel into the space between cylinder head andpiston and means for igniting a mixture of air and fuel in saidcombustion chamber, the improvement wherein:said means for introducingfuel into said space between cylinder head and piston comprises a fuelinjector mounted in the sidewall of said cylinder and located to directa spray of injected fuel into said cylinder toward said exhaust valvethrough a flush opening in said side wall located so as to be covered bysaid piston during fuel combustion.
 7. The improvement according toclaim 6 wherein each cylinder has a single exhaust valve, a singleintake valve and a single fuel injector.
 8. The improvement according toclaim 7 wherein said injector is on the side of said cylinder oppositesaid exhaust valve.
 9. The improvement according to claim 7 wherein saidinjector is on the same side of said cylinder as said exhaust valve. 10.The improvement according to claim 6 wherein at least two injectors areprovided in each of said cylinders with said injectors oriented toinject fuel toward at least one exhaust valve.
 11. The method ofoperating an internal combustion engine having a piston movable in acylinder, a head closing an end of the cylinder opposite the top of saidpiston and forming a combustion chamber therebetween, intake and exhaustvalves communicating with said combustion chamber, means for introducingfuel into said combustion chamber and means for igniting a mixture ofair and fuel in said combustion chamber, comprising the stepsof:injecting a spray of fuel into said cylinder through the sidewall ofsaid cylinder while the top of said piston is below the injection site;maintaining the exhaust valve closed during the injection period;substantially all of said fuel spray being directed against said exhaustvalve: moving said piston upwardly to cover said injection site andcompress the fuel and air into said combustion chamber; and igniting thecompressed fuel and air mixture.
 12. The method according to claim 11wherein said fuel is injected through the sidewall opposite said exhaustvalve.
 13. The method according to claim 11 wherein said fuel isinjected through the sidewall on the same side of the cylinder as saidexhaust valve.
 14. The method according to claim 11 wherein said fuel isinjected simultaneously through the sidewall from opposite sides of saidcylinder.